S&S Cycle SS160-0277 55mm Performance Manifold Black for Harley-Davidson Touring 17-24/Softail 18-24Big bore engines are all about the flow, more air in and more air out, anything that slows that down, robs horsepower. The factory M8 intake manifold does a decent job in stock form, but starts getting in the way when trapped between 124ci and larger cylinders. The stock polymer unit is also less tolerant of the additional heat that a big bore engine can make at full noise. The solution is the new S&S high flow cast aluminum manifold and a must have